Merge branch '2.21' into 2.22

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -15,6 +15,7 @@ No changes since 2.22
 
 No changes since 2.21
 
+2.21.7 (21-Sep-2026)
 2.21.6 (14-Aug-2026)
 2.21.5 (06-Jul-2026)
 2.21.4 (28-May-2026)